Start by lining your 9x9-inch baking pan with parchment paper. This will help you easily lift the fudge out once it’s set. Leave a little overhang on the sides for easy removal later.
In a medium saucepan over medium heat, combine the chopped semi-sweet chocolate, sweetened condensed milk, and butter. Stir gently until everything is melted and smooth. This process should take about 5-7 minutes, so be patient and keep stirring to prevent burning.
Once the chocolate mixture is fully melted and combined, remove the saucepan from the heat. Stir in the pure vanilla extract, mixing until it's fully incorporated.
If you're using chopped nuts or crushed candies, fold them in at this stage. They add a delightful crunch and additional flavor to your fudge.
Pour the luscious chocolate mixture into the prepared baking pan. Use a spatula to spread it evenly, smoothing out the top.
Place the pan in the refrigerator and chill for at least 2 hours, or until the fudge is firm to the touch. If you’re in a hurry, you can also place it in the freezer for about 30 minutes.
Once set, use the parchment overhang to lift the fudge from the pan. Place it on a cutting board and cut it into squares or rectangles. If desired, sprinkle a touch of flaky sea salt on top for that perfect sweet-salty bite.
